The present invention is directed towards a foot exercising device, and more particularly to a foot exercising device which is useful in the prevention of thrombosis of the legs. Devices of this general nature are known in the prior art and exemplified by U.S. Pat. Nos. 3,526,220 and 3,917,261.
Each year nearly 100,000 hospital patients die of pulmonary embolisms. These potentially lethal clots usually form in the leg veins and are often caused by stagnation of blood circulation while the patient is immobile following surgery or illness. Measures have been employed to prevent venous clotting in the legs including anti-coagulants, compression bandages, elastic stockings, leg elevation and early ambulation. For a variety of reasons, none of these has proved to be satisfactorily effective. Patients exhibit a wide range of susceptibility to a standard anti-coagulant dose, which makes adequate prophylactic control difficult. Compression bandages and elastic stockings rarely maintain the necessary uniform compression on the leg veins. Continued leg elevation is difficult to maintain for long periods and imposes an additional load on the cardiovascular system which many patients cannot tolerate. Ambulation often amounts to no more than a few steps around the bed once or twice a day.
There is persuasive clinical evidence that the best method for preventing thromboembolism is to increase the speed of the blood flow in the deep veins of the lower leg. Short of full ambulation (impossible for many post-operative and seriously ill patients), this increase in venous flow velocity is best accomplished by a regimen of leg exercise carried out with adequate duration and frequency.
The purpose of leg exercising devices such as that described in the above-noted patents, as well as that described herein, is to automatically exercise the patient's legs so as to increase blood circulation in the area and thereby prevent the formation of thromboemboli. The prior art foot exercising devices have recognized that it is desirable to run the exercisers in both a passive and an active mode. In the passive mode of operation, the leg exercising device moves the patient's feet up and down through a predetermined arc for a preselected time period. In the active mode of operation, the patient supplies the foot power himself against the resistive pressure which is selected by means of a brake pressure control knob.